In 2006 the Gene Silencing Section, Genetics Branch took delivery of a whole human genome pre-constructed short hairpin RNA (shRNA) library (60,000 clones) initially generated by Drs. G. Hannon (Cold Spring Harbor Laboratory) and S. Elledge (Harvard University). In collaboration with Dr. Paul Meltzers group (Genetics Branch, CCR) three complete replicas of this library have now been grown and quality control analysis has been initiated, including determination of high-throughput protocols for the growing and harvesting of bacteria harboring shRNAs and purification of high quality plasmid DNA. To date we have characterized the silencing mediated by multiple shRNAs corresponding to only a limited number of human genes but envisage that this number will increase rapidly.